#include<iostream>
#include<vector>
#include<queue>
#include<cstring>
#include<cmath>
#include<map>
#include<set>
#include<cstdio>
#include<algorithm>
#define debug(a) cout<<#a<<"="<<a<<endl;
using namespace std;
const int maxn=2e5+1000;
typedef long long LL;
inline LL read(){LL x=0,f=1;char ch=getchar();	while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
return x*f;}
map<char,LL>map1;
int main(void){
   cin.tie(0);std::ios::sync_with_stdio(false);
   LL t;cin>>t;
   while(t--){
       map1.clear();
       LL n;cin>>n;
       string s;
       for(LL i=1;i<=n;i++){
           cin>>s;
           for(auto j:s){
               map1[j]++;
           }
       }
       bool flag=1;
       for(auto i:map1){
          if(i.second%n!=0){
            flag=0;break;
          }
       }
       if(flag){
          cout<<"YES"<<"\n";
       }
       else cout<<"NO"<<"\n";
   }
   return 0;
}
